When I first started playing I could not understand why anyone would pick a single shot AR over all the automatics. I am almost done golding guns and had to move on to the MK. What a difference time with the game makes. I found that the issue with fully automatic rifles is that it takes 4-6 shots to kill, but you can miss a few shots, the rifle can rise up while firing, the person can duck behind something, or they can blast you with 1 shot of a shotgun. BUT, time with the game has made me pretty good at quickly getting hits the first 1 or 2 shots.
So I move on to the MK and find that, since it only needs 2 shots to kill, those are the 2 shots I always made contact with when using autos. All of a sudden I am going from 10 to 14 kills and 4 to 7 deaths to 25 and 2!
This gun is an absolute beast for me and last night I was only 2 deaths from a moab, something I never came close to getting before